1. Field of the Invention
The present invention relates to a method for inspecting insulating film (in the form of a long tape or sheet) for use in production of a film carrier tape for mounting electronic components thereon, such as a TAB (tape automated bonding) tape, a COF (chip on film) tape, a CSP (chip size package) tape, a BGA (ball grid array) tape, a μ-BGA (μ-ball grid array) tape, a FC (flip chip) tape, a QFP (quad flat package) tape, or an FPC (flexible printed circuit) tape (hereinafter such tapes are collectively referred to simply as film carrier tapes); to an inspection apparatus for detecting defects of an insulating film for film carrier tape for mounting electronic components thereon (hereinafter referred to simply as “an insulating film for film carrier tape ”); to a punching apparatus for punching an insulating film for film carrier tape; and to a method for controlling a punching apparatus for punching an insulating film for film carrier tape. More particularly, the present invention relates to a method for inspecting an insulating film for film carrier tape-through employment of a light source of parallel rays, two polarizing filters, an image pickup device, and an image-processing means; to an inspection apparatus for detecting defects of an insulating film for film carrier tape; to a punching apparatus for punching an insulating film for film carrier tape; and to a method for controlling a punching apparatus for punching an insulating film for film carrier tape.
2. Background Art
Film carrier tapes for mounting electronic components thereon are produced through, for example, the following procedure. An insulating film (e.g., polyimide film) is punched to form sprocket holes for conveyance, round holes for mounting solder balls or metal bumps, device holes for mounting, and other holes. After provision of copper foil of a surface of the film, the copper foil is patterned while the insulating film is conveyed by the mediation of, for example, sprocket holes, thereby forming a wiring pattern. If required, a solder resist layer is formed on the wiring pattern, or a metal plating layer is formed on terminal portions. In the production of film carrier tapes such as a BGA tape, an insulating film is punched to form holes such as round holes, and metal bumps, solder balls, or similar conductors are inserted into the round holes, whereby the wiring pattern is connected to electronic components.
Conventionally, during continuous punching of an insulating film for film carrier tape coiled by a reel or a similar part by use of a forward-feeding press or a similar means, sampling inspection during punching has been avoided, from the viewpoint of productivity. Therefore, after punching of a conveyed insulating film for film carrier tape, operators visually find defects such as dents and fins through observation under a microscope. Since the inspection is carried out visually, inspection accuracy has varied among the operators, and some operators have failed to find such defects. Thus, in some cases, defects such as dents remain in a subsequent step and, furthermore, in the products for clients.
In consideration of productivity of punched insulating film for film carrier tapes, more rigorous inspection of the defects such as dents must be carried out at the time of starting punching of coiled insulating film, at the time of replacing insulating film, at the time of terminating punching, and at the time of a periodical quality control procedure. However, when a punched insulating film for film carrier tape is dented due to debris from being lifted or similar abnormality in a punching mold during production thereof or when an insulating film for film carrier tape is dented due to a foreign matter attached on the film per se, a lot of failure pieces are not detected and must be discarded, thereby lowering production yield with respect to the starting material.
In view of the foregoing, Japanese Patent Application laid-Open (kokai) Nos. 10-288586 and 10-293018 and other documents disclose an apparatus for automatically detecting dents of a lead frame, wherein the lead frame conveyed is illuminated, image data of the lead frame are pickuped by a CCD camera, and the pickuped image is processed.
Japanese Patent Application laid-Open (kokai) No. 2000-351025 discloses a method for detecting defects (e.g., dents) of a lead frame during pressing, the method including irradiating a punched lead frame with light emitted from a light-emitting device (i.e., light-emitting diode (LED)) and receiving the light reflected at the surface of the lead frame by a photoreceptor (i.e., photodiode (PD)), thereby detecting abnormalities on a surface of the lead frame.